Among the achievements of present-day electrochemical engineering is the development and commercialization of an increasing variety of electrochemical energy generation and storage devices including high energy lithium-ion rechargeable batteries, high efficiency low cost dye sensitized solar cells (DSSC), and electric double layer capacitors (EDLC or supercapacitors).
The present invention is related to the testing of electrochemical energy generation and storage devices as defined herein including, but are not limited to, batteries, electric double layer capacitors (EDLC's or supercapacitors), certain types of solar cells such as dye sensitized solar cells, and certain fuel cell components. Illustrations of the application of the present invention to the testing of examples of these electrochemical energy generation and storage devices (electrochemical energy devices) are provided.
With time and usage, the electrochemical energy devices mentioned above undergo a reduction in performance (degraded power and energy capacity). This degradation occurs during storage and as a result of electrical energy generation, or of the charge-discharge cycling process in the case of batteries and supercapacitors.
Degradation of electrochemical energy device performance during cycling and storage is a function of numerous factors including temperature, type of electrolyte and electrode materials, discharge level, charge/discharge current values, and storage duration. Power reduction during the operating process is also an inherent feature for electrochemical energy devices
According to data from Sony Corporation, for example, the capacity of their type 26650 Li-ion batteries is reduced by 20% after 500 charge-discharge cycles. The capacity loss of the cylindrical batteries type 18650 (18 mm diameter and 65 mm height) with a LiCoO2 base cathode after 500 cycles is 10-18%. According to the results from studies of cylindrical (type 18650) and prismatic (type 103450) batteries produced by various Japanese and European companies, after 300 charge-discharge cycles at room temperature, the average discharge voltage has dropped by 6% while the average reduction in power for these same batteries was about 21%.
In the process of lithium-ion battery operation (cycling and storage) the positive electrode material can be subject to different conditions within the interior and on the surface that lead to a deterioration of battery performance. During operational cycling at room temperature, the relatively unstable two-phase LiMn2O4 structure transforms to a stable single-phase structure while losing Mn3+ and forming MnO2 that during lithium intercalations is transformed to an inactive LiMnO2 with a lamellar structure. Certain phase changes were also observed in the material of the LiCoO2 based positive electrodes. As a result, during discharge/charge processes the volume of the electrode changes.
Thus, for electrochemical energy devices that contain electrodes and electrolyte, there is a characteristic change in the volume of the electrode structure components distribution (anode, cathode, separator, electrolyte) during operation and even during storage.
In the case of rechargeable batteries, causes of reduced power and the loss of capacity during the cycling process may include the following:                changing of the structure, composition and increasing of the solid electrolyte layer thickness of the surface of electrodes;        change the volume of the electrode structure components distribution (anode, cathode, separator, electrolyte)        changing of the separator properties;        increasing of the gaseous phase concentration in the electrodes material accompanied by the active mass loosening;        forming and disarrangement of the LiCoO2, LiMnO2 laminar structures on the electrodes;        appearing of multitudes of cracks, pores, laminations in the particles of the electrode coating materials;        deactivating of the graphite particles by surface films that increase in thickness due to solvent co-intercalation and insulating of the graphite particles;        increasing of the passive film thickness on the negative carbon electrode surface as a result of the electrical regeneration of the electrolyte;        increasing of the passive film thickness on the aluminum current outlets between the aluminum and cathode active mass.        
As will be clear to one skilled in the art, the methods, apparatus and techniques disclosed in this patent can be used for analogous testing of other electrochemical energy devices having electrodes and electrolytes. These include, but are not limited to, supercapacitors, DSSC solar cells and fuel cell components.
Analysis of the patents dealing with determining electrochemical energy device service life has shown that there are no patents wherein the remaining service life is determined using combined ultrasonic and electromagnetic test methods. The review of the main causes of the power and reversible capacity reduction in electrochemical energy devices during cycling indicates that the capability to carry out effective ultrasonic and electromagnetic testing of electrochemical energy devices for determining the remaining service life would be of great advantage.